JP2017537340A - Lithographic apparatus and device manufacturing method - Google Patents

Abstract

Projecting a patterned beam of radiation onto a plurality of target portions of the substrate on the substrate stage during the exposure stage, followed by a substrate stage (WT) for supporting the substrate (W) in an environment with ambient gas A projection system configured to, a detection system (20, 40) for detecting properties of the substrate on the substrate stage during a detection phase, a reference system, the substrate stage and the reference system An atmospheric lithographic apparatus comprising: a positioning system configured to determine a position of the substrate stage relative to the reference system via a radiation path therebetween, the atmospheric lithographic apparatus comprising: Certain movements with respect to the reference system are performed during the detection phase and other movements with respect to the reference system are performed during the exposure phase. And at least the substrate stage or the reference system is configured to reduce intrusion of the ambient gas into the volume traversed by the radiation path between the substrate stage and the reference system. An outlet system (3) for providing a gas curtain of a working barrier gas, wherein the lithographic apparatus operates such that the characteristics of the gas curtain differ between at least part of the detection stage and within the exposure stage An atmospheric lithography apparatus. [Selection] Figure 3

Description

[Cross-reference of related applications]
[0001] This application claims the benefit of European Patent Application No. 141929298.0 filed on November 13, 2014, which is incorporated herein by reference in its entirety.

  The present invention relates to an atmospheric lithographic apparatus and a device manufacturing method.

  [0003] A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that case, a patterning device, also referred to as a mask or a reticle, may be used to generate a circuit pattern formed on an individual layer of the IC. This pattern can be transferred onto a target portion (eg including part of, one, or more dies) on a substrate (eg a silicon wafer). The substrate can be supported on a substrate stage. Usually, the transfer of the pattern takes place during the exposure stage via imaging of a patterned radiation beam onto a radiation sensitive material (resist) layer provided on the substrate. A projection system is provided for projecting the patterned radiation beam onto the target portion during the exposure phase. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Known lithographic apparatuses include so-called steppers. The stepper irradiates each target portion by exposing the entire pattern onto the target portion at once. Other known lithographic apparatuses include so-called scanners. The scanner irradiates each target portion by scanning the pattern in a certain direction (“scan” direction) with the projection radiation beam and simultaneously scanning the substrate in parallel or antiparallel to this direction.

  [0004] Prior to the exposure stage, the detection stage detects one or more properties of the substrate. At least one of the one or more properties may be detected by the alignment system. For example, in the detection stage, the surface topography of the substrate can be measured. This process is sometimes known as leveling or leveling scanning. In addition or alternatively, the property to be detected may be, for example, the position of the alignment mark on the substrate relative to another alignment mark provided on the substrate stage that supports the substrate. This process is known as alignment or alignment scanning. Properties detected during the detection phase are used during the exposure phase to ensure accurate positioning of the patterned radiation beam on the substrate and / or positioning of the patterned radiation beam on the substrate. To do.

  [0005] In one type of lithographic apparatus, a substrate stage for supporting a substrate is placed in an environment with an ambient gas. Such a lithographic apparatus is called an atmospheric lithographic apparatus. In an atmospheric lithographic apparatus, liquid may be provided between the final element of the projection system and the substrate during the exposure phase. Such an apparatus is often referred to as an immersion lithographic apparatus.

  [0006] The speed at which a lithographic apparatus applies a desired pattern on a substrate, known as throughput, is a key performance criterion in lithographic apparatus. Higher throughput is desirable. Throughput depends on several factors. One factor on which the throughput depends is the speed at which transfer onto the substrate takes place. Another factor on which the throughput depends is the speed at which the nature of the substrate to be detected before pattern transfer can be detected. It is beneficial that the substrate move fast during the exposure phase and / or the detection phase. However, it is important to maintain the accuracy of the measurement, particularly the accuracy of determining the position of the substrate stage relative to the projection system, alignment system, and / or multiple alignment systems, at such fast movement speeds.

  [0007] The measurement radiation beam is used to determine the position of the substrate stage relative to an intermediate, such as a projection system, an alignment system, and / or a plurality of alignment systems, or a grid or reference frame configured to cooperate with an encoder system used. A measurement radiation beam in an atmospheric lithographic apparatus passes through the gas along a radiation path. Local variations in the properties of the gas through which the measurement radiation beam passes can affect the measurement radiation beam. Accordingly, it is an object of the present invention to provide an apparatus that reduces variations in gas properties along the radiation path.

  [0008] According to one aspect of the invention, a substrate stage for supporting a substrate in an ambient gas environment and then patterned radiation on a plurality of target portions of the substrate on the substrate stage during an exposure stage Via a projection system configured to project a beam, a detection system for detecting the nature of the substrate on the substrate stage during the detection phase, a reference system, and a radiation path between the substrate stage and the reference system An atmospheric lithographic apparatus comprising: a positioning system configured to determine a position of the substrate stage relative to the reference system, wherein the atmospheric lithographic apparatus moves the substrate stage relative to the reference system during the sensing phase. And configured to control other movements relative to the reference system during the exposure stage, at least the substrate stay Alternatively, the reference system comprises an outlet system for providing a gas curtain of barrier gas that acts to reduce the penetration of ambient gas into the volume traversed by the radiation path between the substrate stage and the reference system, and lithography The apparatus is provided with an atmospheric lithographic apparatus that operates such that the characteristics of the gas curtain differ between at least part of the detection stage and within the exposure stage.

  [0009] According to one aspect of the present invention, a detection stage for detecting a property of the substrate on the substrate stage in an environment with ambient gas, an exposure stage for exposing the substrate on the substrate stage to a pattern from the patterning device, A device manufacturing method comprising: in a detection stage and an exposure stage, a position of a substrate stage relative to a reference system is determined via a radiation path between the substrate stage and the reference system; A device manufacturing method is provided in which the gas curtain characteristics are different in at least part of the detection stage and in the exposure stage, reducing the penetration of ambient gas into the volume through which the radiation path between the sensor and the reference system passes. The

[00010] Some embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings. In these drawings, the same reference numerals indicate corresponding parts.
FIG. 1 shows a lithographic apparatus according to an embodiment of the invention. FIG. 2 is a cross-sectional view of the substrate stage of the lithographic apparatus. FIG. 3 is a plan view of the substrate stage of FIG. FIG. 4 is a plan view of an outlet system according to still another embodiment. FIG. 5 is two plan views of yet another embodiment of the outlet system. FIG. 6 is a plan view of a first layer and a second layer of still another embodiment. 7 is a cross-sectional view of the outlet system of FIG. FIG. 8 shows two positions, the upper and lower layers of FIGS.

[00011] FIG. 1 schematically depicts a lithographic apparatus according to one embodiment of the invention. This lithographic apparatus
An illumination system (illuminator) IL configured to condition a radiation beam B (eg UV radiation);
A support structure (eg a mask table) constructed to support the patterning device (eg mask) MA and coupled to a first positioner PM configured to accurately position the patterning device according to certain parameters MT,
A substrate stage (eg a wafer table) constructed to hold a substrate (eg resist-coated wafer) W and coupled to a second positioner PW configured to accurately position the substrate according to certain parameters WT,
-Configured to project a patterned radiation beam (formed when the radiation beam B is patterned by the patterning device MA) onto a target portion C (e.g. comprising one or more dies) of the substrate W Projection system (eg, refractive projection lens system) PS.

  [00012] The atmospheric lithographic apparatus comprises an enclosure EN. The enclosure EN encloses at least the substrate stage WT. Ambient gas is present in the enclosure EN.

  [00013] The illumination system IL may be a refractive, reflective, magnetic, electromagnetic, electrostatic, or other type of optical component, or any of them, to induce, shape, or control radiation Various types of optical components, such as any combination, can be included.

  [00014] The support structure MT supports the patterning device, for example, by supporting the weight of the patterning device MA. The support structure MT holds the patterning device MA in a manner that depends on the orientation of the patterning device MA, the design of the lithographic apparatus, and other conditions, such as whether or not the patterning device MA is held in a vacuum environment. The support structure MT may be, for example, a frame or table that can be fixed or movable as required. The support structure MT may ensure that the patterning device MA is at a desired position, for example with respect to the projection system PS. Any use of the terms “reticle” or “mask” herein may be considered synonymous with the more general term “patterning device.”

  [00015] The term "patterning device" as used herein refers to any device that can be used to pattern a cross section of a projection radiation beam so as to create a pattern in a target portion C of a substrate W. Should be interpreted widely. It should be noted that the pattern imparted to the projection radiation beam does not exactly match the desired pattern in the target portion C of the substrate W, for example when the pattern includes a phase shift feature or so-called assist feature. In some cases. Typically, the pattern applied to the radiation beam B to form a patterned radiation beam will correspond to a particular functional layer in a device that is created in the target portion C, such as an integrated circuit.

  [00016] The lithographic apparatus may be of a type having two (dual stage) or more substrate stages WT (and / or two or more mask tables MT). In such a “multi-stage” machine, additional (one or more) substrate stages WT and / or (one or more) mask tables MT can be used in parallel. Alternatively, the preparation process is performed on one or more substrate stages WT and / or mask table MT, while another one or more substrate stages WT and / or mask table MT are used for pattern transfer onto the substrate W. It can also be used.

  [00017] The lithographic apparatus is of a type capable of covering at least a portion of the substrate W with a liquid (eg, water) having a relatively high refractive index so as to fill a space between the projection system PS and the substrate W. It may be. Immersion techniques are well known in the art by increasing the numerical aperture of projection system PS. The term “immersion” as used herein does not mean that a structure, such as a substrate, must be submerged in the immersion liquid, but merely during the transfer of a pattern onto the substrate, the projection system PS. Means that there is immersion liquid between the substrate W and the substrate W.

  [00018] During the exposure phase, the radiation beam B is incident on the patterning device (eg, mask MA), which is held on the support structure (eg, mask table MT), and is patterned by the patterning device. A radiation beam is formed. After passing through the mask MA, the patterned radiation beam passes through the projection system PS, which projects the patterned radiation beam onto the target portion C of the substrate W. Using the second positioner PW and the position sensor IF (eg, a linear encoder having the grid G shown in FIG. 1), for example, the substrate stage WT so as to position the various target portions C in the path of the patterned radiation beam. Can be moved accurately. Similarly, using the first positioner PM and another position sensor (not explicitly shown in FIG. 1), for example, after mechanical removal from the mask library or during scanning, the mask MA is patterned. It can also be accurately positioned with respect to the beam path. In general, the movement of the mask table MT can be achieved by using a long stroke module (coarse positioning) and a short stroke module (fine positioning) that form part of the first positioner PM. Similarly, movement of the substrate stage WT can also be accomplished using a long stroke module and a short stroke module that form part of the second positioner PW. In the case of a stepper (as opposed to a scanner) the mask table MT may be connected to a short stroke actuator only, or may be fixed. Mask MA and substrate W may be aligned using mask alignment marks M1 and M2 and substrate alignment marks P1 and P2. In the example, the substrate alignment marks P1 and P2 occupy the dedicated target portion C. However, the substrate alignment marks P1 and P2 can also be placed in the space between the target portion C and the target portion C (these are the scribe lines). Known as an alignment mark). Similarly, when a plurality of dies are provided on the mask MA, the mask alignment marks P1 and P2 may be placed between the dies.

  [00019] The illustrated lithographic apparatus can be used in scan mode, ie, as a scanner. In scan mode, the mask table MT and the substrate stage WT are scanned synchronously while a patterned radiation beam is projected onto the target portion C (ie, a single dynamic exposure). The speed and direction of the substrate stage WT relative to the mask table MT can be determined by the (reduction) magnification factor and image reversal characteristics of the projection system PS.

  [00020] Prior to the exposure stage, the detection stage detects one or more properties of the substrate. In the detection stage, the surface topography of the substrate can be measured (often referred to as leveling or leveling scan). In addition or alternatively, in the detection stage, the position of the alignment mark on the substrate W relative to the alignment mark on the substrate stage WT may be measured (often referred to as an alignment or alignment scan). The properties detected during the detection phase are used during the exposure phase to ensure accurate positioning of the patterned radiation beam on the substrate W and / or positioning of the patterned radiation beam on the substrate W. Shall.

  [00021] During the exposure phase and the detection phase, the position of the substrate stage WT relative to the reference system RF is determined. A positioning system is provided for determining the position of the substrate stage WT relative to the reference system RF. The positioning system determines the position of the substrate stage WT relative to the reference system RF via a radiation path between the substrate stage WT and the reference system RF. Knowing (i) the position of the substrate stage WT relative to the reference system RF, (ii) the position of the reference system RF relative to the projection system PS, and (iii) the position of the substrate W relative to the substrate stage WT, the substrate W relative to the patterned radiation beam. Can be determined.

  [00022] FIGS. 2 and 3 show an embodiment of a positioning system for determining the position of the substrate stage WT relative to the reference system RF. 2 and 3 are a side view and a plan view of the substrate stage WT, respectively. The positioning system comprises a radiation source 20 for emitting a measurement radiation beam 50 and a sensor 40 for detecting the measurement radiation beam 50. The measurement radiation beam 50 is projected towards the grid G of the reference system RF. In this embodiment, the position of the grid G with respect to the projection system PS is known. In the illustrated embodiment, the reference system RF may be realized by a reference frame indicated with the same abbreviation RF. The position of the grid G with respect to the reference frame RF is known and may or may not be fixed. The position of the reference frame RF relative to the projection system PS is known. The position of the reference frame RF relative to the projection system PS may or may not be fixed. Thus, the grid G is in a known position with respect to the projection system PS. The measurement radiation beam 50 is reflected and / or refracted by the grid G to the sensor 40. The measurement radiation beam 50 travels along the radiation path. Using the sensor 40 configured to detect the measurement radiation beam 50, the position and / or movement of the grid G relative to the radiation source 20 and / or sensor 40 is indicated. The sensor 40 measures the displacement of the substrate stage WT relative to the grid G. Therefore, the position of the substrate stage WT with respect to the projection system PS can be determined. This is possible because the position of the grid G relative to the projection system PS is known as described above.

  [00023] Each combination of radiation source 20 and sensor 40 is most conveniently positioned at a respective corner of the substrate stage WT (see FIG. 3 described in detail below). This position is an advantageous position because the center of the substrate stage WT is occupied by the substrate W. Further, each pair of the symmetrically arranged combinations is used to determine the angular displacement of the substrate stage WT about an axis parallel to the Z axis (see FIG. 1). The angular displacement can be determined with higher accuracy as the distance between the symmetrically arranged combinations is larger. For more detailed background, see, for example, US Pat. No. 7,602,489 to Van der Pasch et al., Which is incorporated herein by reference.

  [00024] As described above, the positioning system uses the measurement radiation beam 50. The measurement radiation beam 50 travels along the radiation path. The ambient gas through which the measurement radiation beam 50 along the radiation path passes can affect this measurement radiation beam 50.

  [00025] How the measurement radiation beam 50 propagates through the gas can be influenced by several factors. For example, gas temperature, gas humidity, and gas composition are factors that can affect the refractive index of the gas. Local variations in these factors and turbulence in the gas can make the refractive index of the gas non-uniform. The measurement radiation beam 50 passing through the gas is affected by refractive index variations. For example, a change in refractive index can change the trajectory of the measurement radiation beam 50. In addition, or alternatively, a change in refractive index can cause a wavefront error in the measurement radiation beam 50. Measurement errors can be induced by refractive index variations along the radiation path. Measurement errors can cause positioning errors when positioning components of the lithographic apparatus. Such positioning errors can adversely affect overlay and / or focus because the placement of the patterned radiation beam on the substrate W can change.

  [00026] Known configurations correspond to attempts to reduce the refractive index variation of the gas in the volume traversed by the radiation path. For example, in one embodiment, an outlet system 3 is provided. The outlet system 3 is configured to provide a gas curtain 13 of barrier gas that acts to reduce the ambient gas in the enclosure EN from entering the volume traversed by the radiation path. Thus, the gas in the volume through which the measurement radiation beam 50 passes is controllable.

  [00027] The known outlet system 3 ejects barrier gas from at least one opening 30 in the surface of the substrate stage WT. The barrier gas forms a gas curtain 13 and obstructs the flow of ambient gas on one side of the gas curtain 13. A gas curtain 13 may be provided around the volume so that gas within the volume is effectively separated from ambient gas outside this volume. The gas in the volume can be adjusted to be more uniform than the gas outside the volume. Thus, the gas curtain 13 can be used to provide a barrier around the volume through which the radiation path of the measurement radiation beam 50 passes. This protects the measurement radiation beam 50 from the effects of changes in ambient gas outside the volume. A gas in the volume is called a protected gas.

  [00028] If unadjusted ambient gas enters the volume, it affects the propagation of the measurement radiation beam 50 and may induce errors. The outlet system 3 uses various methods to prevent ambient gas from entering the volume by the gas curtain 13. Such various methods include (i) providing a jet of barrier gas through a set of openings 30 in the substrate stage WT, and (ii) a second set of radially outer sides in the substrate stage WT. With respect to the laminar volume of the thermally regulated barrier gas provided through the openings, the turbulence of the barrier gas through the first set of radially inner openings in the substrate stage W that radially surrounds the volume. Including, but not limited to, providing. For completeness, it is noted here that the flow of barrier gas through the first set of openings on the radially inner side may be turbulent or laminar.

  [00029] However, tests on the known outlet system 3 showed that as the moving speed increased, more unadjusted ambient gas entered the volume and contaminated the protected gas.

  [00030] While the substrate stage WT relatively moves in the surrounding gas of the enclosure EN, the flow of the surrounding gas to the substrate stage WT is induced as follows. By the movement of the substrate stage WT in the enclosure EN, the surrounding gas is pushed out from the path of the substrate stage WT on one side of the substrate stage WT that functions as the front side of the moving substrate stage WT. This extrusion causes an increase in the pressure of the surrounding gas on the front side of the substrate stage WT. The movement of the substrate stage WT also causes a drop in the pressure of ambient gas on one side of the substrate stage WT that functions as the rear side of the moving substrate stage WT. Due to the pressure difference of the ambient gas between the front side of the substrate stage WT and the rear side of the substrate stage WT, a flow of ambient gas from the front side to the rear side of the substrate stage WT occurs.

  [00031] Any flow of ambient gas on the substrate stage WT applies an inward force to the gas curtain 13. The inward force on the gas curtain 13 increases as the ambient gas flow rate increases. The speed of the ambient gas flow increases as the speed of the substrate stage WT relative to the enclosure EN increases. As the inward force increases, ambient gas from outside the volume traversed by the radiation path is forced into the volume. The gas that penetrates into the volume in this way can be called breakthrough.

  [00032] If the moving speed is high and / or the moving duration is long, break-through into the volume due to thermally unadjusted ambient gas can be significant. A high moving speed is desirable for increasing throughput.

  [00033] The present invention aims to reduce breakthrough while limiting acoustic disturbances generated by the outlet system 3. The present invention is based on the insight that the various types of movement performed by the substrate stage WT during various stages of operation of the atmospheric lithographic apparatus. For example, during the detection phase, the substrate stage WT typically moves relative to the reference frame RF at a faster rate than during the exposure phase. The faster the substrate stage WT with respect to the reference frame RF, the higher the possibility of breakthrough. During the detection phase, the length of movement between the direction changes relative to the reference frame RF is considerably longer than during the exposure phase. The inventors have found that this leads to a breakthrough because the time for the ambient gas flow to cause sufficient instability in the gas curtain 13 is lengthened. Furthermore, the moving direction of the substrate stage WT relative to the reference frame RF is mainly unidirectional in the detection stage, and is more evenly distributed among various directions in the exposure stage.

  [00034] The existing outlet system 3 is optimized for cases where the substrate stage WT is at a constant high speed relative to the reference frame RF during an infinitely long movement duration in a given direction. Yes. In order to withstand such a constant high speed, a gas curtain 13 is created using a high-speed barrier gas for the outlet system 3 when exiting the outlet system 3. A high barrier gas velocity with respect to the outlet system 3 is undesirable because of acoustic disturbances in the apparatus. The slower the barrier gas velocity with respect to the outlet system 3, the smaller the acoustic disturbance.

In the present invention, characteristics of the gas curtain 13 different from those in the exposure stage are used in at least a part of the detection stage. The characteristics of the different gas curtains 13 are optimized to withstand breakthrough for at least part of the exposure and detection stages, while reducing acoustic disturbances by using the slowest possible barrier gas velocity. .

  [00036] In one embodiment, during the transition between the detection phase and the exposure phase, the characteristics of the gas curtain 13 change from one characteristic to another.

  [00037] In yet another embodiment, the characteristics of the gas curtain 13 may differ during other stages of the lithographic apparatus or during sub-stages of operation. As an example of another stage, there is a movement stage in which the substrate stage WT moves between a position where the detection stage is performed and a position where the exposure stage is performed. Examples of the sub-stage of the operation include a leveling scan and an alignment scan which are sub-stages of the detection stage. It may be beneficial to use different characteristics of the gas curtain 13 between the leveling scan and the alignment scan. This is because the maximum speed of the substrate stage WT relative to the reference frame RF during the alignment scan is different (eg, lower) than the maximum speed of the substrate stage WT relative to the reference frame RF during the leveling scan. In one embodiment, the characteristics of the gas curtain 13 are the same in the exposure stage and in the alignment scan sub-stage of the scan stage, but different in the level scan sub-stage of the scan stage.

  [00038] The present invention contemplates using two or more different characteristics of the gas curtain 13 for different stages of the lithographic apparatus or sub-stages of operation.

  [00039] In the present invention, the operating characteristics of the outlet system 3 (that is, the characteristics of the gas curtain 13) vary depending on the type of movement expected during the current operating phase. The changing characteristics include (i) the speed of the barrier gas as it exits the outlet system 3, (ii) the amount of barrier gas exiting the outlet system 3 per unit time, and (iii) exiting the outlet system 3. It includes the spatial distribution of the barrier gas in plan view. If the outlet area of the outlet system 3 does not change, (i) and (iii) are substantially the same. By changing the characteristics, at least (i) during at least part of the detection stage (eg sub-stage) and (ii) the barrier gas as it exits the outlet system 3 compared to prior art machines The speed of the outlet system 3 can be reduced. As a result, acoustic disturbances due to the high speed of the barrier gas to the outlet system 3 as it exits the outlet system 3 can occur during at least part of the detection phase and / or during the exposure phase as compared to prior art machines. Will be reduced for a while.

  [00040] For movements that are likely to cause breakthrough (movements with high speed and / or long distance between direction changes), barrier gas exiting the outlet system 3 at higher speeds is used. When the speed is slow and / or when the distance between changes in the direction of movement of the substrate stage WT is short, the barrier gas exiting the outlet system 3 is used at a slower speed, thereby reducing acoustic disturbances.

  [00041] The difference in the movement of the substrate stage WT relative to the reference system between at least part of the detection phase and the exposure phase is the main direction of travel of the substrate stage WT relative to the reference frame RF. Therefore, when the geometric shape (for example, spatial distribution) in the plan view of the gas curtain 13 formed by the barrier gas is not circular, one of the detection stage or the sub-stage of the detection stage and the exposure stage is May have different geometry and / or orientation of the gas curtain 13.

  [00042] Several embodiments of an outlet system 3 having an outlet system controller 100 are described below. In each of these embodiments, of the speed of the barrier gas as it exits the outlet system 3, the amount of barrier gas exiting the outlet system 3 per unit time, and the spatial distribution of the barrier gas as it exits the outlet system 3 One or more can vary.

  [00043] The present invention is described below with reference to FIG. In FIG. 2, the substrate stage WT houses at least one outlet system 3. The state in which the substrate stage WT is at the imaging position below the projection system PS is illustrated. However, in one embodiment, the at least one outlet system 3 is part of the reference frame RF and is mounted with the radiation source 20 and the sensor 40 substantially stationary with respect to the projection system PS. (For example, it may be accommodated on the reference frame RF). In such an embodiment, the grid G is not part of the reference system and moves with the substrate stage WT and is in a known position relative to the substrate stage WT (eg, fixed to the substrate stage WT).

  [00044] In one embodiment, the grid G that is part of the reference system is additionally in the measurement position. The properties of the substrate W placed on the substrate stage WT, such as the position of the substrate W on the substrate stage WT, the surface topography of the substrate W, and the like are measured at the measurement position. In this embodiment, the grid G may be positioned above the substrate stage WT (similar to the main embodiment described above) or positioned on the substrate stage WT as described in the previous paragraph. Also good.

  [00045] Four outlet systems 3 are shown on the substrate stage WT of FIG. The substrate stage WT may include other objects not shown, such as an object configured to hold the substrate W. Each outlet system 3 is configured to provide a gas curtain 13 that functions to reduce the inflow of ambient gas into the volume traversed by the radiation path between the substrate stage WT and the reference system RF. Each of the illustrated outlet systems 3 includes at least one opening 30 in the substrate stage WT. At least one opening 30 in the substrate stage WT is adapted to flow a barrier gas to build a gas curtain 13 that encloses a portion of the volume traversed by the radiation path.

  FIG. 3 shows a first embodiment of the outlet system 3. A plurality of individual openings 30 in the upper surface of the substrate stage WT surround the radiation source 20 and the sensor 40. The controller 100 individually controls the flow of barrier gas exiting from each opening 30 of the outlet system 3. The controller 100 controls the speed of the barrier gas with respect to each opening 30 as it exits each opening 30. The speed of the barrier gas with respect to each opening may be the same for each of the plurality of openings 30. In another embodiment, the speed of the barrier gas for each opening 30 may vary between the openings 30. For example, in any of the openings 30 aligned with the radiation source 20 and / or the sensor 40 in the principle direction of the substrate stage WT, the flow rate of the gas exiting from the opening is larger than the flow rate of the gas exiting from the other opening 30. Also good. The controller 100 changes the speed of the barrier gas for each opening 30 during the exposure phase compared to at least part of the detection phase (eg, leveling scan sub-step). (I) The speed of the substrate stage WT relative to the reference frame RF is slower during the exposure stage than during part of the detection stage, and (ii) the time between changes in the direction of movement of the substrate stage WT is Because the exposure stage is shorter than at least a part (e.g., leveling scan sub-stage), the controller 100 determines the speed of the barrier gas exiting each opening 30 during the exposure stage as part of the detection stage (e.g., Lower than during leveling scan sub-stage). As a result, the acoustic disturbance generated by the barrier gas during the exposure stage is smaller than when the barrier gas does not slow down the respective opening 30 when exiting each opening 30 during the exposure stage.

  [00047] Although the embodiment of FIG. 3 shows multiple openings 30 for each outlet system 3, there may alternatively be a single elongated opening.

  The embodiment of FIG. 3 has been described above with respect to the speed relative to the opening 30 when exiting the outlet system 3. However, in another embodiment, the controller 100 may instead control the amount of barrier gas exiting the opening 30 per unit time.

  [00049] FIG. 4 shows still another embodiment similar to the embodiment of FIG. 3 except for the points described below. In the embodiment of FIG. 4, the outlet system 3 includes a first elongate opening 210 and a second elongate opening 230. The controller 100 controls a valve 220 that selects whether barrier gas is provided to the first elongate opening 210 or the second elongate opening 230.

  [00050] The first elongate opening 210 and the second elongate opening 230 each surround the radiation source 20 and the sensor 40. Each of the first elongate opening 210 and the second elongate opening 230 may be provided as a groove, or may be formed by a plurality of individual openings.

  [00051] The geometry of the first elongated opening 210 is configured to be used during the exposure phase. The geometric shape of the first elongated opening 210 is configured for movement of the substrate stage WT that does not have a main direction of travel. That is, the geometric shape of the first elongated opening 210 is such that the gas curtain 13 has good resistance to breakthrough in progress in any horizontal direction of the substrate stage WT (that is, in the xy plane). Configured to provide.

  [00052] The geometry of the second elongate opening 230 is configured to be used during at least a portion of the detection stage (eg, leveling scan sub-stage). The geometry of the second elongate opening 230 is configured to provide a gas curtain 13 that is particularly resistant to breakthrough during the illustrated lateral movement. This is the main direction of movement of the substrate stage WT during at least a portion of the detection stage (eg, leveling scan sub-stage). Thus, for a given speed of barrier gas to the outlet system 3 as it exits the outlet system 3, the geometry of the second elongate opening 230 is greater than the geometry of the first elongate opening 210. High resistance to breakthrough during movement in the left-right direction shown in the drawing.

  [00053] Similar to the embodiment of FIG. 3 and all other embodiments, the controller 100 determines the speed of the barrier gas to the outlet system 3 when exiting the outlet system 3 and / or the barrier gas exiting the outlet system 3 per unit time. The amount can be varied. The controller 100 can vary the speed and / or amount depending on whether it is in the exposure phase or a predetermined portion of the detection phase (eg, leveling scan sub-step).

  FIG. 5 shows yet another embodiment of the outlet system 3. The embodiment of FIG. 5 is the same as the embodiment of FIG. 3 except the points described below. The opening geometry that provides the barrier gas during at least a portion of the detection stage (eg, leveling scan sub-stage) provides an opening that provides the barrier gas during the exposure stage (and optionally the remainder of the detection stage) It has a similar concept to the embodiment of FIG. 4 in that it is different from the geometric shape of FIG.

  [00055] A plurality of elongated openings are provided. The controller 100 controls which of the plurality of openings is supplied with gas. An inner opening 310 and an outer opening 320 are provided. The inner opening 310 has a square shape in plan view. The outer opening 320 is two V-shaped and has a direction away from the radiation source 20 and the sensor 40 in the main direction of travel of the substrate stage WT during at least a part of the detection stage (eg leveling scan sub-stage). It has a V-shape with facing sides. There are a total of four flow directors 330, one at each corner of the inner opening 310 (for clarity, only one guide is shown in FIG. 5). ). When the direction of the flow guide 330 is changed under the control of the controller 100, the first outlet geometry or the second outlet geometry can be selected. On the left side of FIG. 5, a first outlet geometry is shown oriented to the side selected for use during the sensing phase. The first geometric shape is composed of the outer opening 320 and the top and bottom of the inner opening 310. On the right side of FIG. 5, the flow guide 330 is turned to select a second outlet geometry having a substantially square shape. The second outlet geometry includes all of the inner openings 310 and does not include any outer openings 320. The second outlet geometry on the right side of FIG. 5 is used during the exposure phase (and optionally part of the detection phase). Each of the flow guides 330 is oriented to transition the geometry from the second outlet geometry to the first outlet geometry during at least a portion of the sensing stage (eg, leveling scan sub-stage). Can be changed.

  FIG. 6 shows an upper layer 410 and a lower layer 420 in still another embodiment of the outlet system 3 in a plan view. FIG. 7 shows a cross-section of the embodiment of FIG. 6, and FIG. 8 shows in plan view the state in which the upper layer 410 and the lower layer 420 overlap. The embodiment of FIGS. 6-8 includes a first outlet geometry used during at least a portion of the detection stage (eg, leveling scan sub-stage) and a second outlet geometry used during the exposure stage. 5 is similar to the embodiment of FIG. 5 in that the geometric shape of the opening to which the barrier gas is supplied can be changed.

  [00057] In the embodiment of Figs. 6 to 8, the upper layer 410 and the lower layer 420 are provided so as to overlap each other. Movement of the upper layer 410 relative to the lower layer 420 changes the geometry of the opening through which the barrier gas is provided. Translational movement of the upper layer 410 relative to the lower layer 420 between the exposure phase and at least a portion of the detection phase (eg, leveling scan sub-step) allows a change in outlet geometry.

  [00058] On the left side of FIG. 6, a lower layer 420 is shown. The openings of the first geometry and the second geometry are present such that both are centered with respect to the position of the opening relative to the radiation source 20 and the sensor 40.

  [00059] On the right side of FIG. 6, an upper layer 410 is shown. An opening is provided for the first outlet geometry and the second outlet geometry. However, the first outlet geometry and the second outlet geometry are offset from each other with respect to the radiation source 20 and the sensor 40. When the upper layer 410 and the lower layer 420 are superposed, and the upper layer 410 is moved with respect to the lower layer 420 and a barrier gas is provided by applying pressure from below both layers, any of the openings in the upper layer 410 may be provided. It is possible to select whether the barrier gas is allowed to flow through the portion.

  [00060] A lithographic apparatus according to at least one of the embodiments described above may be used for irradiating a substrate with a projection radiation beam in a device manufacturing method.

  [00061] Although specific reference is made herein to the use of a lithographic apparatus in IC manufacturing, the lithographic apparatus described herein is an integrated optical system, a guidance pattern and a detection pattern for a magnetic domain memory, It should be understood that other applications such as the manufacture of flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads and the like may be had. As will be appreciated by those skilled in the art, in such other applications, the terms “wafer” or “die” as used herein are all more general “substrate” or “target” respectively. It may be considered synonymous with the term “part”. The substrate described herein may be used, for example, a track (usually a tool for applying a resist layer to the substrate and developing the exposed resist), a metrology tool, and / or an inspection tool before and after exposure. May be processed. Where applicable, the disclosure herein may be applied to substrate processing tools such as those described above and other substrate processing tools. Further, since the substrate may be processed multiple times, for example, to make a multi-layer IC, the term substrate as used herein may refer to a substrate that already contains multiple processing layers.

  [00062] While specific reference has been made to the use of embodiments of the present invention in the context of optical lithography as described above, it will be appreciated that the present invention may be used in other applications, such as imprint lithography. However, it is not limited to optical lithography if the situation permits. In imprint lithography, the topography within the patterning device defines the pattern that is created on the substrate. The topography of the patterning device is pressed into a resist layer supplied to the substrate, whereupon the resist is cured by electromagnetic radiation, heat, pressure, or a combination thereof. The patterning device is moved out of the resist leaving a pattern in it after the resist is cured.

  [00063] The present invention relates to a particular configuration of a lithographic apparatus having a grid G on a reference system RF and each combination of a respective radiation source 20 and a respective sensor 40 housed in a substrate stage WT. This has been described in the specification and the accompanying drawings. The invention also applies to other configurations of a lithographic apparatus having a grid G on the substrate stage WT and each combination of a respective radiation source 20 and a respective sensor 40 housed in a reference system RF. Is possible.

  [00064] As used herein, the terms "radiation" and "beam" refer to ultraviolet (UV) (eg, wavelengths of 436 nm, 405 nm, 365 nm, 355 nm, 248 nm, 193 nm, 157 nm, or 126 nm, or approximately these As well as all types of electromagnetic radiation, including fine particle beams such as ion beams and electron beams.

  [00065] The term "lens" can refer to any one or combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic, and electrostatic optical components, depending on the context. .

  [00066] While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described.

[00067] The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.

Claims (4)

A substrate stage for supporting the substrate in an environment with ambient gas;
A projection system configured to project a patterned beam of radiation onto a plurality of target portions of the substrate on the substrate stage during an exposure stage;
A detection system for detecting a property of the substrate on the substrate stage during a detection stage;
A reference system;
An atmospheric lithographic apparatus comprising: a positioning system configured to determine a position of the substrate stage relative to the reference system via a radiation path between the substrate stage and the reference system;
The atmospheric lithographic apparatus is configured to control the substrate stage to perform certain movements relative to the reference system during the detection phase and to perform other movements relative to the reference system during the exposure phase;
At least the substrate stage or the reference system provides a gas curtain of barrier gas that acts to reduce penetration of the ambient gas into the volume traversed by the radiation path between the substrate stage and the reference system. Has an outlet system for
The lithographic apparatus acts such that the characteristics of the gas curtain differ between at least part of the detection stage and within the exposure stage;
Atmospheric lithography equipment. The characteristics are:
The speed of the barrier gas relative to the outlet system upon exiting the outlet system;
The amount of the barrier gas exiting the outlet system per unit time;
At least one of a spatial distribution of the barrier gas upon exiting the outlet system,
The atmospheric lithographic apparatus according to claim 1. A detection stage for detecting the properties of the substrate on the substrate stage in an environment with ambient gas;
An exposure step of exposing a pattern from a patterning device to the substrate on the substrate stage, comprising:
In the detection step and the exposure step, the position of the substrate stage with respect to a reference system is determined via a radiation path between the substrate stage and the reference system, and a gas curtain of barrier gas is formed between the substrate stage and the reference. Reducing the penetration of the ambient gas into the volume through which the radiation path to and from the system passes,
The characteristics of the gas curtain are different in at least part of the detection stage and in the exposure stage,
Device manufacturing method. The characteristics are:
The speed of the barrier gas relative to the substrate stage;
The amount of the barrier gas exiting the outlet system for providing the gas curtain per unit time;
At least one of a spatial distribution of the barrier gas with respect to the substrate stage,
The device manufacturing method according to claim 3.

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